Like all electronics, gas sensors wear out over time and require replacement. You can expect typical electromechanical sensors for ordinary gases like hydrogen sulfide and carbon monoxide to last between two and three years under normal conditions. Sensors that test for rarer gases, such as hydrogen fluoride, degrade sooner and require replacement as soon as 12-18 months.
What Are the Ideal Conditions for Maximum Gas Sensor Longevity?
Environmental conditions in your building play a large part in your gas sensors’ life span. A temperature of 20 °C with a relative humidity of 60 percent will give your gas sensors the longest possible life. In fact, with such favorable conditions, electromechanical sensors have functioned properly for more than 11 years.
Occasional contact with the toxic gases themselves doesn’t degrade the sensor’s tiny fuel cells. Reputable manufacturers produce sensors with ample amounts of catalyst material, so high-quality sensors don’t degrade with normal use.
Another variable to consider when estimating a gas sensor’s lifespan is its “shelf” or “storage” life. When stored at the recommended temperature of 20 °C, they should only last for six months from the date of manufacture. So it would be best if you didn’t try to keep many on hand unless you plan on replacing them soon.
How To Anticipate Gas Sensor Replacement?
If you know how long your sensor will last, you’re in a better position to plan its replacement. With such knowledge, you could have the sensors on hand with a minimum of storage time, reduce equipment downtime, and limit service calls.
On the one hand, you want to get the longest possible use out of a sensor, but on the other, if you stretch it out too long, the sensors may lose adequate sensitivity and fail between service visits. Conversely, if you schedule your replacements based solely on the manufacturers’ recommendations, you may often throw money away replacing sensors with substantial life left in them.
What Factors Cause Your Sensors Quickly?
Unfavorable humidity and temperature levels are the two factors most likely to degrade your gas sensors. If your building’s environment varies from the manufacturer’s recommendations for extended periods, it reduces your gas sensors’ life span.
Typical manufacturer specifications for gas sensors specify an operating temperature range of between -30 and +50 °C. The highest quality H2S or CO sensors can withstand short-term exposure to temps as high as 60-65 °C. However, keep in mind that repeated exposure to high temperatures causes the sensor’s electrolyte to evaporate, which can skew the baseline reading and impair its response time.
While gas sensors operate at temperatures as low as -40 °C, they lose as much as 85 percent of their sensitivity past -30 °C. Their electrolytes can also freeze when it reaches -35 °C.
Extreme humidity is the most detrimental environmental factor for your gas sensors, and 60 percent relative humidity is ideal. Above that level, the sensor’s electrolytes absorb water from the air, which dilutes it. In extreme humidity, the sensor’s liquid content can rise by a factor of two or three and eventually leak through the body and pins.
When the humidity is too low, the sensor begins to dehydrate. Dry gas sensors have slower response times.
Whether fixed or portable, gas sensors are a necessary life safety device and required for certain buildings by the Ontario Fire Code. You must test and replace them when they fail.
If your daily responsibilities don’t allow you enough time to stay on top of your gas sensor testing and replacement, then contact the fire safety experts at All Protect Systems, Inc. They’ve been providing the greater Ontario area with fire alarm systems, fire extinguishers, emergency/exit lighting, and gas detection systems since 1996.